Production of a bleaching liquor containing performic acid



United States Patent 3,374,177 PRODUCTION OF A BLEACI-IING LIQUOR CONTAINING PERFORMIC ACID Gswald Schmidt, Frankenthal, Pfalz, and Karl Heinz Ruecker, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany No Drawing. Filed July 6, 1965, Ser. No. 469,897 Claims priority, application Germany, July 10, 1964, B 77,609, B 77,610 12 Claims. (Cl. 252-486) ABSTRACT 6F THE DISCLGSURE A process for the production of a bleaching liquor containing performic acid by bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) at least one substance yielding either formaldehyde, a low molecular weight formic ester or a low molecular weight formamide, the hydrogen peroxide being present in an amount equivalent to one to twelve times that of the substances (b).

The present invention relates to a process for the production from hydrogen peroxide of a bleaching liquor containing performic acid for the treatment of textile fibrous material.

It is known that keratinous fibrous material may be bleached with aqueous liquors containing performic acid as the oxidizing bleaching agent. Strange to say it has been found that the bleaching action and stability of such liquors is dependent on the method by which the performic acid has been prepared. Thus it is known that more stable performic acid bleaching liquors can be prepared from formaldehyde and hydrogen peroxide in the presence of acids than from formic acid and hydrogen peroxide. In the prior art method using formaldehyde as an initial material, liquors having a particularly strongbleaching action are moreover obtained when a concentrated stock bleaching solution is first prepared and then diluted for use.

The prior art method gives very good results as regards bleaching but it has the disadvantage that to achieve optimum results it is necessary to use free formaldehyde. This may lead, particularly when used on a large scale, to inconvenience and danger for the personnel carrying out the method.

It has also been found that the pH value of the bleaching liquor drops considerably during use in the case of prior art method. The activity of the liquor is thus changed during bleaching and this may have an unfavourable effect on the bleaching action. If this is to be avoided, the pH value of the liquor must be constantly controlled and corrected and this involves additional labour.

It is an object of this invention to prepare a bleaching liquor containing performic acid in a particularly simple Way. Another object is to prevent troublesome odors in the production of the bleaching liquor. It is also an object to prepare a bleaching liquor whose pH value undergoes only negligible change during use. A further object is to provide a solid stable mixture of substances which by simple dissolution in water and mixing with hydrogen peroxide in an acid medium will give a bleaching liquor containing performic acid. Other objects of the invention will be evident from the following description.

We have found than an active and surprisingly stable bleaching liquor containingperformic acid can be pre- Patented Mar. 19, 1968 ice pared without using free formaldehyde by reacting (a) hydrogen peroxide and (b) at least one substance yielding formaldehyde or a low molecular weight formic ester or a low molecular weight formamide in an acid to neutral aqueous solution at a temperature of up to 60 C. the resultant solution may then be diluted if desired and adjusted to a pH value of 1 to 8.5, preferably 2 to 8.5.

Substances yielding formaldehyde are defined as substances which contain at least once a group having the general formula:

in which Y denotes a nitrogen or oxygen atom, X denotes a nitrogen or oxygen atom or the group SO M, M being a proton, an ammonium ion, an alkali metal ion or half an alkaline earth metal ion, andthe valencies of the said nitrogen and/or oxygen atoms which are not attached to the central carbon atom being, in the absence of a $0 M group, at the most partly saturated by hydrogen.

Examples of substances which contain at least once a group having the Formula I are: formaldehyde polymers, such as trioxymethylene, tetraoxymethylene and paraformaldehyde; formals, such as dimethylformal and diethylformal; hydroxymethanesulfonic acid; aminomethanesulfonic acid; imino-bis-methanesulfonic acid and N-alkyl and N-hydroxyalkyl derivatives of these two acids; nitrilotrismethanesulfonic acid, ammonium salts, alkali metal salts and alkaline earth metal salts of these acids, such as preferably the sodium, potassium and calcium salts; N-methylol compounds of carbamides, such as particularly urea, imidazolidones, tetrahydrotriazinones, hexahydropyrimidones and urones; of melamines, of dicyanodiamide; and also ethers of such N-methylol compounds with alcohols having one to five carbon atoms.

Examples of low molecular weight formic esters and formamides are substances having the general formula:

Q II

in which Q denotes a radical OR or R being an alkyl radical having one to five carbon atoms, R being a hydrogen atom or an alkyl radical having one to five carbon atoms and R being a hydrogen atom or an alkyl radical having one to five carbon atoms. Examples of substances having the Formula II are: methyl formate, ethyl formate, propyl formate, butyl formate and diethylformamide.

The drop in the pH value during bleaching may be prevented or minimized by employing or additionally employing substances containing at least one group having the Formula I or substances having the Formula II which form amines or preferably ammonia by reaction With hydrogen peroxide. A particularly suitable and therefore preferred substance of this type is hexamethylene tetramine. Formamide, dimethylformamide, aminomethanesulfonic acid, iminobismethanesulfonic acid, their alkyl derivatives, particularly their methyl derivatives, and their salts however act in this way.

The following are preferred substances from the group (b) because they are solid at room temperature, particularly stable and easily accessible: formaldehyde polymers, such as trioxymethylene, tetraoxymethylene and paraformalclehyde; hydroxymethanesulfonic acid and its sodium, potassium and calcium salts; the reaction products of this acid with ammonia, i.e., aminomethanesultonic acid, aminobismethanesul-fonic acid and nitrilotrismethanesulfonic acid and the sodium, potassium and calcium salts of these acids and hexamethylene tctramine.

Substances of the abovementioned type are reacted with hydrogen peroxide in aqueous medium. The speed of this reaction is dependent on the hydrogen ion concentration of the medium. An acid or neutral range is used to achieve rapidly a bleaching solution which is ready for use. The acid reaction may be produced by adding inorganic or organic acids or acid salts. The acids may be chosen at will. Strong acids are very suitable, such as sulfuric acid and sulfonic acids, and acid salts such as sodium bisulfite and sodium bisulfate. The amount of acid substance required depends on its acidity. Amounts of 0.5 to of strong acids, with reference to the weight of hydrogen peroxide to be reacted, are adequate, whereas 10 to 50% of weaker acids or acid salts may be necessary. It seems as though even in acid solution, the reaction to form performic acid does not immediately proceed to the point of completely exhausting one reaction component; rather there is apparently set up an equilibrium condition which continues during bleaching and consequently during consumption of performic acid, as long as all the reactants are still present.

It has proved to be very suitable to coemploy stabilizers for active oxygen in the present process. These stabilizers are particularly advantageous when it is intended to carry out bleaching at elevated temperature, particularly above 50 C. because under these conditions they prevent too rapid delivery of the active oxygen with consequent yellowing and even damage to the material being bleached. Stabilizers for active oxygen are known per se; examples are alkali metal polyphosphates, such as tetrasodium pyrophosphate, and more highly condensed phosphates such as sodium tripolyphosphate, sodium tetraphosphate and sodium hexapolyphosphate; magnesium silicate; magnesium phosphate; and complex-forming aminopolycarboxylic acids, such as particularly nitrilotriacetic acid and ethylene dia'minotetracetic acid and their ammonium salts, magnesium-alkali metal salts and alkali metal salts. Alkali metal polyphosphates, particulary those of sodium and potassium, nit-rilotriacetic acid, ethylene diaminotetracetic acid and the sodium, potassium and magnesium salts of these acids are preferred.

The stabilizers for active oxygen may be used singly or more than one of them may be additionally used. Generally it is not necessary to use them in amounts of more than with reference to the weight of anhydrous hydrogen peroxide.

Finally, wetting agents, detergents and/ or softening agents and also optical brighteners which are stable to peroxides may be added to the liquor at any stage during its production.

Hydrogen peroxide is advantageously used in the process according to this invention in amounts which are one to twelve times, preferably three to ten times the amount which is equivalent to the substance (b). In other words:

The ratio betwen substances which contain at least one group having the Formula I or substances having the Formula II and hydrogen peroxide is preferably chosen so that for each mole of groups having the Formula I or of substance having the Formula II, one to twelve moles of hydrogen peroxide are available; particularly successful results are achieved with a molar ratio of 1:3 to 1:10.

The amount of hydrogen peroxide depends on whether it is desired to bleach in a long liquor or with a padding liquor. Amounts of hydrogen peroxide of from 10 i to 30 cc./l. have proved to be particularly useful for long liquors and from 40 to 130 cc./l. for padding liquors.

The perforrnic acid bleaching liquor may be prepared by adding the ingredients direct to the liquor in the amounts desired for bleaching. Alternatively a concentrated stock bleaching solution may first be prepared which is diluted to the concentration for use immediately prior to use. Stock bleaching solutions may be prepared in concentrations which are equivalent to 100 to 500 cc./l. of 35% hydrogen peroxide. When preparing stock bleaching solutions it is recommendable that the temperature should not exceed 40 C.; bleaching liquors to which the ingredients are added direct may however be prepared at higher temperatures up to about 60 C.

The bleaching liquor, which if necessary has been cliluted to the concentration required for use, may be adjusted to a pH value of from 1 to 8.5, preferably from 4 to 6, if it does not have such a pH value by virtue of its method of production. The usual alkaline or acid reacting reagents, particularly weak or medium strength bases or acids, may be used for the purpose. It is preferable to adjust the pH value in the presence of the material to be bleached because the latter sometimes contains acid or alkaline substances which may change the pH value of the bleaching liquor.

The process according to this invention is particularly convenient and advantageous when, in carrying it out, use is made of a stable agent which contains in the correct prOpOrtions the components Which in water with hydrogen peroxide will give a bleaching liquor ready for use. A particularly advantageous agent of this type contains 50 to 20% by weight of condensed alkali metal phosphate, by weight of hydroxymethanesulfonic acid or its ammonium, alkali metal (particularly sodium or potassium), or alkaline earth metal (particularly calcium) salts, 10 to 20% by weight of condensed alkali metal phosphate, particularly sodium or potassium phosphates, and 10 to 0% by weight of ethylene diaminotetracetic acid or its ammonium, alkali metal (particularly sodium or potassium), or alkaline earth metal (particularly magnesium) salts. The agent may also contain solid acids or acid salts. Such an agent may be used for example as follows: for each liter of bleaching liquor, 20 cc. of 35% hydrogen peroxide is mixed with 20 cc. of water, 3 to 7 g. of the agent is dissolved therein and the solution is made up to 1 liter with water. The bleaching liquor thus prepared is ready for immediate use without further measures.

The process according to this invention yields performic acid bleaching liquors which are distinguished by remar"- able stability and bleaching power in a particularly simple and convenient way.

The liquors may be used for example for bleaching textile materials of polyamide, polyester, polyacrylonitrile, cellulose, cellulose ester and regenerated cellulose fibers. They are particularly suitable for bleaching textile material which contains or consists of protein fibers, for example, wool, silk and animal hairs, and also feathers, bristles and the like.

The liquors may be used for the said purpose in conventional ways. For example the following bleaching conditions have proved to be suitable for bleaching wool: A high degree of whiteness is obtained in a long liquor at 50 C. in two to six hours. Equally good results are achieved at C. in about thirty minutes and in the neighborhood of the boiling point in ten to twenty minutes.

The batchwise and continuous padding method is particularly suitable for piece goods and tops. The material is padded with the bleaching solution on a padding machine. The padded material can then be rolled up, Wrapped round with a waterproof sheet and kept in slow rotary movement at room temperature for five to fifteen, preferably five to ten, hours. To shorten the treatment period, the padded material may be heated in a tunnel (to 40 C. or more) and then kept in movement in a reaction chamber at elevated temperature. A considerable shortening of the bleaching period is thus achieved. This bleaching method may also be carried out continuously by passing the padded material in open width at temperatures of 80 to 105 C. through a steamer at such a rate that the optimum bleaching period corresponding to the temperature is achieved.

The invention is further illustrated by the following examples in which parts and percentages are by weight.

EXAMPLE 1 An agent for the production of a bleaching liquor containing performic acid has the following composition:

55 parts of sodium hydroxymethanesulfonate, 22 parts of hexamethylenetetramine, 15 parts of sodium tripolyphosphate, 6 parts of ethylenediaminotetracetic acid and 2 parts of sodium bisulfite.

30 liters of 35 hydrogen peroxide and then 7.5 kg. of the agent described above in paragraph 1 are added to 2,000 liters of Water in a wood, stoneware or alloyed steel winch dyeing machine having a capacity of 3,000 liters. A bleaching bath is immediately obtained which is ready for use and whose wetting out property may be improved by adding 0.6 kg. of octylphenol heptaglycol ether.

The winch dyeing machine is charged with 50 kg. of unbleached piece goods of wool and polyacrylonitrile (70:30) for bleaching. The whole is left for five minutes at room temperature, the pH value of the liquor is controlled and if necessary adjusted to 5.5 with ammonia or formic acid. The temperature is then raised in about fifteen minutes to 80 C. and kept steady for thirty minutes. The pH value remains practically constant during this bleaching. The material is then thoroughly rinsed hot and cold and further treated in any desired way. The material has a high degree of whiteness after this bleach.

EXAMPLE 2 A cheese dyeing machine of alloyed steel (liquor capacity 750 liters) is filled with 50 kg. of dry blended yarn (wool and rayon staple 70:30) in the form of cheeses on the material carrier. 15 liters of 35% hydrogen peroxide is added to 735 liters of water in an attached container and there is dissolved therein 3.5 kg. of a mixture having the following composition:

50 parts of sodium imino-bis-methanesulfonate, 25 parts of hexamethylene tetramine, 12 parts of ethylenediaminotetraacetic acid, parts of sodium pyrophosphate and 3 parts of sodium bisulfiite.

250 g. of an optical brightener having the formula:

r onr CH CzH O which is stable to peroxides and goes on to both fibers from a weak acid medium is dissolved in water and added to the bleaching solution made as described above. The liquor thus prepared is pumped into the machine. To expel enclosed air, the liquor is allowed to circulate for about ten minutes. Then 0.15 kg. of nonylphenol monoglycol ether, dissolved in a little water, is added and dispersed as a wetting agent. While the liquor is circulated it is heated in fifteen minutes to 70 C. and the material is treated for forty-five minutes at this temperature. The pH value of the bleaching liquor is 5.3 at the beginning and 5.6 at the end of the bleaching period. After the liquor has been drained olf, the material is rinsed hot and cold. 5 kg. of previously dissolved condensation product of 2 moles of stearic acid and 1 mole of diethylene triamine, which has been partly acetylated with 1 mole of acetic anhydride, is added to the final rinsing liquor as a softener, the liquor is made slightly acid with acetic acid (pH 5 .5 to 6.5) and allowed to circulate for ten minutes at room temperature. A yarn is thus obtained which has a high degree of whiteness and a soft, pleasant handle.

EXAMPLE 3 Precleaned dry woollen piece goods are padded at room temperature on a padding machine with a liquor (liquor retention which contains 80 cc./l. of 35% hydrogen peroxide, 20 g./l. of the mixture described in paragraph 1 of Example 1 and 1.5 g./l. of octylphenol heptaglycol ether and has a pH value of 5.5. In the preparation of the padding liquor, the hydrogen peroxide is first mixed with an equal amount of water and then the solids are dissolved in this solution by stirring at room tempera! ture.

After the goods have been padded, they are heated to 60 C. in a shaft, then rolled up, wrapped round with a moisture-proof plastics sheet and left rotating in a reaction chamber for two hours at 60 C. The bleached material is then rinsed on an open width Washing machine. The material exhibits a good bleaching effect.

EXAMPLE 4 Precleaned piece goods of wool and polyester (60:40) having a moisture content of 60% are padded with the same solution as described in Example 3 at room temperature (squeezed out to 100%) and heated in a shaft to C. After the goods have been padded they are not rolled up but proceed continuously into a steamer in which they remain for a total of fifteen to twenty minutes at C. or for ten minutes at C. They are then rinsed. The goods thus acquire a beautiful white color.

EXAMPLE 5 A pack dyeing machine (600 liters capacity), which contains washed, moist pig bristles having a dry Weight of 35 kg, is charged with 500 liters of a bleaching solution which has been prepared from 7.5 liters of 35% hydrogen peroxide and 1.5 kg. of a mixture which has been prepared from 50 parts of sodium nitrilomethanesulfonate, 20 parts of hexamethylene tetramine, 20 parts of sodium phosphate, 5 parts of sodium ethylene diaminotetracetate and 5 parts of ethylene diamine tetracetic acid. The pH value of the bleaching liquor adjusts itself to 7.3. The circulating liquor is brought to a temperature of 85 C. in fifteen minutes and kept at this temperature for twenty-five minutes. The pH value of the liquor falls during bleaching into the acid region and remains at 6.1. The material is then rinsed thoroughly both hot and cold. Very beautifully bleached bristles are obtained.

EXAMPLE 6 25 liters of 35 hydrogen peroxide is added in an alloyed steel winch dyeing machine (capacity 2,500 liters) to 2,000 liters of water at 35 C., well dispersed and 6 kg. of the mixture described in Example 5 is dissolved therein. Then 0.4 kg. of octylphenyl heptaglycol ether is added. The winch dyeing machine is then charged with 75 kg. of nylon-6 piece goods, the pH value of the bleaching liquor is tested and, if necessary, adjusted to 7.0 with ammonia or formic acid. The temperature of the bleaching liquor is then raised to 80 C. in fifteeen minutes and kept at this temperature for thirty minutes. The pH value of the liquor changes during this period to 6.3.

EXAMPLE 7 Precleaned dry woollen piece goods are padded as described in Example 3. After having been padded, the material is rolled up, wrapped in a moistureproof sheet of plastic and left to rotate for eight hours at room temperature (22 C.). The bleached material is then rinsed on an open Width washing machine, squeezed out and dried. The Woollen piece goods thus bleached exhibit a very high degree of whiteness.

7 EXAMPLE 8 A wooden winch dyeing machine (2,500 liters capacity) is filled with 2,200 lters of soft water at 22 C. 40 liters of 35 hydrogen peroxide is added and also 7 kg. of a mixture consisting of:

57 parts of trioxymethylene, 20 parts of sodium iminomethanesulfonate, 3 parts of sodium bisulfite, 15 parts of sodium pyrophosphate and 5 parts of ethylenediarninotetracetic acid. 0.5 kg. of octylphenyl heptaglycol ether is added to the solution. The winch is then charged with 70 kg. of piece goods of wool and polyester (70:30). The pH value of the bleaching liquor is 6.0. The temperature is raised to 60 C. in ten minutes and maintained for fifty minutes. The pH value of the liquor rises during bleaching to 6.6. Material having a high degree of whiteness is thus obtained.

EXAMPLE 9 100 kg. of blended yarn of wool and polyacrylonitrile (90: in the form of cheeses is introduced on a material carrier into a cheese dyeing machine of alloyed steel (liquor capacity 1,500 liters). In an attached container, 30 liters of 35% hydrogen peroxide is added to 1,455 liters of water. 6 kg. of a mixture of 50 parts of dimethylolurea, 8 parts of sodium bisulfite, 18 parts of sodium bisulfate, 5 parts of hexamethylene tetramine, 10 parts of sodium pyrophosphate and 9 parts of ethylenediaminotetra-cetic acid is dissolved in this liquor. The liquor is allowed to circulate for five minutes to expel the enclosed air. Then 0.2 kg. of nonylphenol monoglycol ether is dissolved in a little water and added and dispersed in the liquor. While the liquor is circulating, the temperature is raised to 90 C. in fifteen minutes and maintained for twenty minutes. The pH value of the bleaching liquor is 5.3 at the commencement and rises to 5.7 at the end of the bleaching. The goods thus bleached exhibit a high degree of whiteness.

EXAMPLE 10 5 liters of 35% hydrogen peroxide, 0.75 liter of 10% sulphuric acid, 0.5 liter of formamide and 1.35 liters of water are mixed at C. A stock bleaching solution is thus formed.

The stock solution obtained according to paragraph 1 is added to 500 liters of water in the attached container of an alloyed steel or stoneware pack dyeing machine which is charged with 50 kg. of precleaned loose wool. The diluted liquor is pumped onto the material to be bleached, adjusted with sulphuric acid to a pH value of 5 and, while the liquor is circulating, heated to 50 C. and kept at this temperature for 2 /2 hours; the pH value changes only slightly to 5.3. The goods are rinsed hot and cold.

Instead of treating the goods for 2 /2 hours at 50 C., bleaching may also be carried out in thirty minutes at 80 C. In this case 0.5 liter of a solution of the magnesium disodium salt of ethylene diaminotetracetic acid is added to the bleaching liquor as an oxygen stabilizer. The goods are bleached excellently after this treatment.

EXAMPLE 11 25 liters of a stock bleaching solution (previously prepared from 2.5 liters of 10% sulfuric acid, 16.75 liters of hydrogen peroxide and 5.75 liters of dimethylformamide) is aded to 1,000 liters of water in a tops dyeing machine. Then 2 kg. of tetrasodium pyrophosphate is added as an oxygen stabilizer and 0.2 kg. of nonylphenol heptaglycol ether as a wetting agent. The material carrier, with 75 kg. of wool tops on bobbins, is then introduced. The pH value of the bleaching liquor adjusts itself to 4.8. The liquor is allowed to circulate for ten minutes to expel the air and is then heated to 90 C. and left for twenty minutes at this temperature. The pH value of the liquor rises during this period to 5.7. The material is slowly cooled and thoroughly rinsed by adding water. The goods thus treated are bleached excellently.

EXAMPLE 12 A wooden feather washer provided with a stirring means and having a liquor capacity of 1,200 liters is charged with 25 kg. of washed unbleached bed feathers which are still moist and then charged with 1,000 liters of a bleaching solution which contains 25 liters of stock bleaching solution prepared as described in Example 11. The pH value of the bleaching solution is 4.7. The bleaching liquor is heated to 50 C. and left at this temperature for 2 /2 hours, the pH value thus rising to 5.3. The feathers are then rinsed hot and cold, hydroextracted and dried in a steamer. Excellently bleached feathers are obtained.

EXAMPLE 13 30 liters of a stock bleaching solution composed as follows: 3 parts of methyl formate, 60 parts of 35 hydrogen peroxide, 2 parts of 10% sulfuric acid and 35 parts or" water, is added to 2,000 liters of water (12 hardness, German scale) at 20 C. in a wooden winch dyeing machine having a capacity of 2,500 liters. In this bleaching liquor there are dissolved 1.5 kg. of tetrasodium pyrophosphate and 1.5 kg. of a 35% solution of sodium ethylenediaminotetracetate as stabilizer for the active oxygen and 0.3 kg. of octylphenol heptaglycol ether. 60 kg. of woollen piece goods is introduced. The pH value of the bleaching liquor is 7.0. The temperature is raised in fifteen minutes from 20 to C. and maintained for thirty-five minutes. The pH value of the liquor undergoes only slight change (to 6.7) during bleaching. The goods bleached in this way exhibit an excellent degree of whiteness.

EXAMPLE l4 Precleaned dry piece goods of wool and polyester (55:45) are padded in a padding machine with cc./l. of a bleaching solution (liquor retention 80%) having the following composition: 10 parts of diethylformamide, 65 parts of 35% hydrogen peroxide, 15 parts of 10% sulfuric acid and 10 parts of water.

The padding liquor also contains 1.2 g./l. of octylphenol heptaglycol ether and 5 g./l. of sodium pyrophosphate.

The goods, after they have been padded, are heated to 80 C. in a shaft, then rolled up, wrapped in a moistureproof plastics film and allowed to rotate for thirty minutes at 80 C. in a thermo-dwell chamber. The goods are then rinsed. The goods exhibit an excellent bleaching effect.

EXAMPLE 15 Precleaned dry woolen piece goods are padded as described in Example 14 with the same bleaching solution. The liquor retention is The padded goods are rolled up, wrapped in a moistureproof sheet and allowed to rotate for seven hours at 22 C. Excellently bleached goods are thus obtained.

We claim:

1. In a process for the production of a bleaching liquor containing performic acid from hydrogen peroxide the improvement which comprises bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula in which Y is a member selected from the group consisting of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said nitrogen and/ or oxygen atoms which are not attached to the central carbon atom being, in the absence of an 80 M group, at the most partly saturated by hydrogen, a formic ester having up to six carbon atoms in the molecule, and a formamide having up to carbon atoms in the molecule, the hydrogen peroxide being present in an amount equivalent to one to twelve times that of the substances (b).

2 In a process for the production of a bleaching liquor Containing performic acid from hydrogen peroxide, the improvement which compri es bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula in which Y is a member selected from the group consisting of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and -SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said .nilrogen and/or oxygen atoms which are not attached to the central carbon atom being, in the absence of an 50 M group, at the most partly saturated by hydrogen, a formic ester having up to six carbon atoms in the molecule, and a formamide having up to five carbon aloms in the molecule, the hydrogen peroxide being present in an amount equivalent to one to twelve times that of the substances (b), diluting the resultant solution and adjusting the pH value thereof to 2 to 8.5.

3. In a process for the production of a bleaching liquor containing performic acid, from hydrogen peroxide, the improvement which comprises bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula in which Y is a member selected from the group consisting of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said nitrogen and/or oxygen atoms which are not attached to the central carbon atom being, in the absence of an SO M group, at the most partly saturated by hydrogen, a formic ester having up to six carbon atoms in the molecule, and a formamide having up to five carbon atoms in the molecule, the hydrogen peroxide being present in a concentration of to 500 cc./l. (calculated as solution) and in an amount equivalent to three to ten times that of the substances (b) and diluting the solution formed to a concentration corresponding to 10 to-130 cc./l. of 35% hydrogen peroxide.

4. In a process for the production of a bleaching liquor from hydrogen peroxide the improvement which comprises bringing together at a temperature of up to 60 C. in acid to neutral aqueous solution (a) hydrogen peroxide and (h) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula Y-CH X, in which Y is a member selected from the group consisting of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said nitrogen and/or oxygen atoms which are not attached to the central carbon atom being, in the absence of an $0 M group, at the most partly saturated by hydrogen, a formic ester having up to six carbon atoms in the molecule and 21 formamide having up to five carbon atoms in the molecule, the hydrogen peroxide being present in a concentration of 10 to 500 cc./l. (calculated as a 35% solution) and in an amount equivalent to three to ten times that of substance (b), diluting the resultant solution to a concentration which is equivalent to 10 to cc./l. of 35% hydrogen peroxide, and adjusting the pH value to 2 to 8.5.

5. In a process for the production of a bleaching liquor contairing performic acid from hydrogen peroxide, the improvement which comprises bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula in which Y is a member selected from the group consistiig of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said nitrogen and/ or oxygen atoms which are not attached to the central carbon atom being, in the absence of an $0 M group, at the most partly saturated by hydrogen, a formic ester having up to 6 carbon atoms in the molecule and a formamide having up to five carbon atoms in the molecule and (c) a conventional stabilizer for active oxygen, said stabilizer being selected from the group consisting of sodium, potassium polyphosphate, a complex-forming aminopolycarboxylic acid, and the sodium, potassium, and magnesium salt of such an acid, the hydrogen peroxide being present in an amount equivalent to one to twelve times that of the substances (b).

6. A bleaching liquor prepared according to the process of claim 1.

7. A bleaching liquor prepared according to the process of claim 2.

8. A bleaching liquor prepared according to the process of claim 3.

9. A bleaching liquor prepared according to the process of claim 4.

It A bleaching liquor prepared according to the process of claim 5.

11. An agent for the production of a bleaching liquor containing performic acid, comprising 50 to 20% by weight of hexamethylene tetramine, 30 to 60% by weight of a member selected from the group consisting of hydroxymethanesulfonic acid and an ammonium, alkali 1116131 and alkaline earth metal salt thereof, 10 to 20% by Weight of a phosphate selected from the group consisting of condensed sodium phosphate, condensed potassium phosphate and 10 to 0% by weight of a member selected from the group consisting of ethylenediaminotetracetic acid and an ammonium, sodium, potassium or magnesium salt thereof.

12. In a process for the production of a bleaching liquor containing perforrnic acid from hydrogen peroxide the improvement which comprises bringing together at a temperature of up to 60 C. in an acid to neutral aqueous solution (a) hydrogen peroxide and (b) a compound selected from the group consisting of at least one substance yielding formaldehyde, said substance containing at least one group having the general formula in which Y is a member selected from the group consisting of nitrogen and oxygen, X is a member selected from the group consisting of nitrogen, oxygen, and SO M, M being a member selected from the group consisting of a proton, an ammonium ion, a sodium ion, a potassium ion, and half a calcium ion, and the valencies of the said nitrogen and/or oxygen atoms which are not attached to the central carbon atom being, in the absence of an 50 M group, at the most partly saturated by 11 12 hydrogen, a formic ester having up to six carbon atoms 2,860,945 11/1958 Dustman 252186 X in the molecule, and a formarnide having up to five car- 3,193,445 7/1965 Parker et 21 s 252-186 X bon atoms in the molecule, the hydrogen peroxide being FOREIGN PATENTS present in an amount equivalent to one to twelve times that of the substances (1)) and at least one of the sub- 5 923 845 4/1963 Great Bummstances (17) forming ammonia by reaction with hydrogen OTHER REFERENCES peroxide. Cam b n n C A u p e 001 Bleaching, Niagara Fal1s,l\.1., led References Wed May 26, 1950, published Mar. 6, 1951. UNITED STATES PATENTS 1,063,679 6/1913 Hartman et a1 252-1s1s X LEON ROSDOL Pl'mm 2,7ZO,44O 19/1955 Wallace 252136 X M. WEENBLATT, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,374 ,177 March 19, 1968 Oswald Schmidt et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 32, "condensed alkali metal phosphate," should read hexamethylene tetramine, 30 to 60% line 73, "to 40" should read to 50 Column 7, line 3, "lters" should read liters Signed and sealed this 2nd day of December 1969.

(SEAL) Attest:

Eg n Fletcher, 1 WILLIAM E. SCHUYLER'; JR.

Attesting Officer Commissioner of Patents 

